There is often a need with electronic systems to determine the occurrence of events associated with the operation of those electronic systems. Further, electronic systems are also used to monitor and detect events that are occurring on other equipment or within the environment within which the electronic system is placed. As such, there is often a need to determine timing information associated with the occurrence of these monitored and detected events. The resolution or precision with which this timing information can be provided depends upon the timing detection and measurement systems utilized to determine when the event has occurred.
Current techniques for detecting the occurrence of an event and timing associated with the occurrence of an event typically fall into one of three different categories. The first category uses timestamps based on conventional counters, which are limited by the frequency at which the counter can operate, typically on the order of several nanoseconds. The second category, used in time interval counters, utilizes circuits that rely upon analog techniques to determine time intervals, such as charging a capacitor with a constant current source and measuring the resulting voltage. These analog techniques, however, can only measure relatively short time intervals (microseconds) and require calibration to remain accurate (e.g., annual calibration traceable to an official timing source such as from the National Institute of Standards and Technology (NIST)). The third category uses the propagation delay of circuit elements, such as gates or wires, to subdivide a measurement interval in to sub-intervals. These propagation delay techniques also require calibration because the switching speed of the circuitry changes as a function of process, temperature and voltage. These propagation delay techniques also become cumbersome as the number of sub-intervals grow.
While these prior systems and techniques provide the ability to detect and determine time information associated with the occurrence of events, it is desirable to be able to achieve greater resolution in determining timing information associated with detected events.